Accessing hadronic form factors at large momentum transfers has traditionally presented a challenge for lattice QCD simulations. Here, we demonstrate how a novel implementation of the Feynman-Hellmann method can be employed to calculate hadronic form factors in lattice QCD at momenta much higher than previously accessible. Our simulations are performed on a single set of gauge configurations with three flavors of degenerate mass quarks corresponding to $m_{\pi }\approx 470\mathrm{MeV}$. We are able to determine the electromagnetic form factors of the pion and nucleon up to approximately $6{\mathrm{GeV}}^2$, with results for the ratio of the electric and magnetic form factors of the proton at our simulated quark mass agreeing well with experimental results.

We study the transport coefficients from the QCD Kondo effect in quark matter which contains heavy quarks as impurity particles. We estimate the coupling constant of the interaction between a light quark and a heavy quark at finite density and temperature by using the renormalization group equation up to two-loop order. We also estimate the coupling constant at zero temperature by using the mean-field approximation as nonperturbative treatment. To calculate the transport coefficients, we use the relativistic Boltzmann equation and apply the relaxation time approximation. We calculate the electric resistivity from the relativistic kinetic theory, and the viscosities from the relativistic hydrodynamics. We find that the electric resistivity is enhanced and the shear viscosity is suppressed due to the QCD Kondo effect at low temperature.

Hot QCD medium effects have been studied in the effective quasiparticle description of quark-gluon plasma. This model encodes the collective excitation of gluons and quarks/antiquarks in the thermal medium in terms of effective quarks and gluons having nontrivial energy dispersion relation. The present investigation involves the extension of the effective quasiparticle model in strong magnetic field limit. Realizing hot QCD medium in the strong magnetic field as an effective grand canonical system in terms of the modified quark, antiquark, and gluonic degrees of freedom, the thermodynamics has been studied. Further, the Debye mass in hot QCD medium has to be sensitive to the magnetic field, and subsequently the same has been observed for the effective hot QCD coupling. As an implication, electrical conductivity (longitudinal) has been studied within an effective kinetic theory description of hot QCD in the presence of the strong magnetic field. The hot QCD equation of state dependence entering through the effective coupling and quasiparton distribution function is found to have a significant impact on the longitudinal electrical conductivity in the strong magnetic field background.

We study two kinds of inelastic meson-meson scattering. The first kind is inelastic 2-to-2 meson-meson scattering that is governed by quark interchange as well as quark-antiquark annihilation and creation. Cross-section formulas are provided to get unpolarized cross sections for $\pi K\to \rho K^{*}$ for $I=1/2$, $\pi K^{*}\to \rho K$ for $I=1/2$, $\pi K^{*}\to \rho K^{*}$ for $I=1/2$, and $\rho K\to \rho K^{*}$ for $I=1/2$. Near threshold, quark interchange dominates the reactions near the critical temperature. The second kind is 2-to-1 meson-meson scattering with the process that a quark in an initial meson and an antiquark in another initial meson annihilate into a gluon and subsequently the gluon is absorbed by the other antiquark or quark. The transition potential for the process is derived. Four Feynman diagrams at tree level contribute to the 2-to-1 meson-meson scattering. Starting from the $S$-matrix element, the isospin-averaged unpolarized cross section with transition amplitudes is derived. The cross sections for $\pi \pi \to \rho$ and $\pi K\to K^{*}$ decrease with increasing temperature.

We calculate the single spin asymmetry for the $ep\to e\mathrm{\Delta }(1232)$ process, for an electron beam polarized normal to the scattering plane. Such single spin asymmetries vanish in the one-photon exchange approximation and are directly proportional to the absorptive part of a two-photon exchange amplitude. As the intermediate state in such a two-photon exchange process is on its mass shell, the asymmetry allows one to access for the first time the on-shell $\mathrm{\Delta }\to \mathrm{\Delta }$ as well as $N^{*}\to \mathrm{\Delta }$ electromagnetic transitions. We present the general formalism to describe the $ep\to e\mathrm{\Delta }$ beam normal spin asymmetry, and we provide a numerical estimate of its value using the nucleon, $\mathrm{\Delta }(1232)$, $S_{11}(1535)$, and $D_{13}(1520)$ intermediate states. We compare our results with the first data from the Qweak@JLab experiment and give predictions for the A4@MAMI experiment.

The dominant contribution to the Higgs production in association with the bottom quark pair at the LHC is the gluon-gluon fusion parton subprocess. We present a complete calculation of the next-to-leading order electroweak corrections to this channel. The other small contributions with quarks in the initial state are calculated at tree level. We find that the next-to-leading order electroweak corrections can suppress the leading order contributions significantly.

Semi-inclusive charge-changing neutrino reactions on targets of heavy water are investigated with the goal of determining the relative contributions to the total cross section of deuterium and oxygen in kinematics chosen to emphasize the former. The study is undertaken for conditions where the typical neutrino beam energies are in the few GeV region, and hence relativistic modeling is essential. For this, the previous relativistic approach for the deuteron is employed, together with a spectral function approach for the case of oxygen. Upon optimizing the kinematics of the final-state particles assumed to be detected (typically a muon and a proton) it is shown that the oxygen contribution to the total cross section is suppressed by roughly an order of magnitude compared with the deuterium cross section, thereby confirming that $\mathrm{CC}\nu$ studies of heavy water can effectively yield the cross sections for deuterium, with acceptable backgrounds from oxygen. This opens the possibility of using deuterium to determine the incident neutrino flux distribution, to have it serve as a target for which the nuclear structure issues are minimal, and possibly to use deuterium to provide improved knowledge of specific aspects of hadronic structure, such as to explore the momentum transfer dependence of the isovector axial-vector form factor of the nucleon.

The results of a search for squarks and gluinos in final states with an isolated electron or muon, multiple jets and large missing transverse momentum using proton-proton collision data at a center-of-mass energy of $\sqrt{s}=13\mathrm{TeV}$ are presented. The data set used was recorded during 2015 and 2016 by the ATLAS experiment at the Large Hadron Collider and corresponds to an integrated luminosity of $36.1{\mathrm{fb}}^{-1}$. No significant excess beyond the expected background is found. Exclusion limits at 95% confidence level are set in a number of supersymmetric scenarios, reaching masses up to 2.1 TeV for gluino pair production and up to 1.25 TeV for squark pair production.

LUX was the first dark matter experiment to use a ${}^{83\mathrm{m}}\mathrm{Kr}$ calibration source. In this paper, we describe the source preparation and injection. We also present several ${}^{83\mathrm{m}}\mathrm{Kr}$ calibration applications in the context of the 2013 LUX exposure, including the measurement of temporal and spatial variation in scintillation and charge signal amplitudes, and several methods to understand the electric field within the time projection chamber.

Radiation from accelerating mirrors in a Minkowski spacetime provides insights into the nature of horizons, black holes, and entanglement entropy. We introduce new, simple, symmetric and analytic moving mirror solutions and study their particle, energy, and entropy production. This includes an asymptotically static case with finite emission that is the black hole analog of complete evaporation. The total energy, total entropy, total particles, and spectrum are the same on both sides of the mirror. We also study its asymptotically inertial, drifting analog (which gives a black hole remnant) to explore differences in finite and infinite production.

It was shown by Jacobson in 1995 that the Einstein equation can be derived as a local constitutive equation for an equilibrium spacetime thermodynamics. With the aim to understand if such thermodynamical description is an intrinsic property of gravitation, many attempts have been made so far to generalize this treatment to a broader class of gravitational theories. Here we consider the case of the Einstein-Cartan theory as a prototype of theories with nonpropagating torsion. In doing so, we study the properties of Killing horizons in the presence of torsion, establish the notion of local causal horizon in Riemann-Cartan spacetimes, and derive the generalized Raychaudhuri equation for these kinds of geometries. Then, starting with the entropy that can be associated to these local causal horizons, we derive the Einstein-Cartan equation by implementing the Clausius equation. We outline two ways of proceeding with the derivation depending on whether we take torsion as a geometric field or as a matter field. In both cases we need to add internal entropy production terms to the Clausius equation as the shear and twist cannot be taken to be 0 a priori for our setup. This fact implies the necessity of a nonequilibrium thermodynamics treatment for the local causal horizon. Furthermore, it implies that a nonzero twist at the horizon in general contributes to the Hartle-Hawking tidal heating for black holes with possible implications for future observations.

The unimodular version of the ghost-free higher derivative gravity is obtained. It is the unimodular reduction of some particular Lagrangians quadratic in curvature.

Gravitational-wave observation together with a large number of electromagnetic observations shows that the source of the latest gravitational-wave event, GW170817, detected primarily by advanced LIGO, is the merger of a binary neutron star. We attempt to interpret this observational event based on our results of numerical-relativity simulations performed so far, paying particular attention to the optical and infrared observations. We finally reach a conclusion that this event is described consistently by the presence of a long-lived hypermassive or supramassive neutron star as the merger remnant because (i) significant contamination by lanthanide elements along our line of sight to this source can be avoided by the strong neutrino irradiation from it and (ii) it could play a crucial role in producing an ejecta component of appreciable mass with fast motion in the postmerger phase. We also point out that (I) the neutron-star equation of state has to be sufficiently stiff (i.e., the maximum mass of cold spherical neutron stars, $M_{\max }$, has to be appreciably higher than $2M_{\odot }$) in order for a long-lived massive neutron star to be formed as the merger remnant for the binary systems of GW170817, for which the initial total mass is $\gtrsim 2.73M_{\odot }$, and (II) the absence of optical counterparts associated with relativistic ejecta suggests a not-extremely-high value of $M_{\max }$ approximately as $2.15–2.25M_{\odot }$.

Various classes of fishnet Feynman graphs are shown to feature a Yangian symmetry over the conformal algebra. We explicitly discuss scalar graphs in three, four and six spacetime dimensions as well as the inclusion of fermions in four dimensions. The Yangian symmetry results in novel differential equations for these families of largely unsolved Feynman integrals. Notably, the considered fishnet graphs in three and four dimensions dominate the correlation functions and scattering amplitudes in specific double-scaling limits of planar, $\gamma$-twisted $\mathcal{N}=4$ super Yang–Mills or Aharony-Bergman-Jafferis-Maldacena (ABJM) theory. Consequently, the study of fishnet graphs allows us to get deep insights into the integrability of the planar $\mathrm{AdS}/\mathrm{CFT}$ correspondence.

A recent LHCb measurement of the ratio $R_{K^{*}}$ of $B\to K^{*}\mu \overline{\mu }$ to $B\to K^{*}e\overline{e}$ branching fractions has produced results in mild tension with the standard model (SM). This adds to the known anomalies also induced by the $b\to s\ell \overline{\ell }$ transitions, resulting in a confidence level now as high as $4\sigma$. We analyze whether the parameter space preferred by all the $b\to s\ell \overline{\ell }$ anomalies is compatible with a heavy $Z^{\prime }$ boson assumed to have nonuniversal couplings to SM fermions dictated by the principle of minimal flavor violation (MFV). We deal with the MFV couplings of the $Z^{\prime }$ to leptons in the context of the type-I seesaw scenario for generating neutrino masses. The flavor-violating $Z^{\prime }$ interactions are subject to stringent constraints from other processes, especially $B\text{−}\overline{B}$ mixing, charged lepton decays ${\ell }_i\to {\ell }_j{\ell }_k{\overline{\ell }}_l$ occurring at tree level, and the loop induced $\mu \to e\gamma$. We perform scans for parameter regions allowed by various data and predict the ranges for a number of observables. Some of the predictions, such as the branching fractions of lepton-flavor violating $\tau \to 3\mu$, $B\to Ke\mu$, $K_L\to e\mu$, and $Z\to \ell {\ell }^{\prime }$, are not far below their experimental bounds and therefore could be probed by searches in the near future. The viable parameter space depends strongly on the neutrino mass hierarchy, with a preference for the inverted one.

We estimate the smallest branching ratio for the Higgs decay channel $h\to \mu \tau$, which can be probed at an $e^{+}{e}^{-}$ collider, and compare it with the projected reach at the high-luminosity run of the LHC. Using a model-independent approach, Higgs production is considered in two separate cases. In the first case, $hWW$ and $hZZ$ couplings are allowed to be scaled by a factor allowed by the latest experimental limits on $hWW$ and $hZZ$ couplings. In the second case, we have introduced higher-dimensional effective operators for these interaction vertices. Keeping $\mathrm{BR}(h\to \mu \tau )$ as a purely phenomenological quantity, we find that this branching ratio can be probed down to $\approx 2.69\times {10}^{-3}$ and $\approx 5.83\times {10}^{-4}$, respectively, at the 250 GeV and 1000 GeV runs of an $e^{+}{e}^{-}$ collider.

We present a minimal left-right dark matter framework that can simultaneously explain the recently observed 3.55 keV x-ray line from several galaxy clusters and gauge coupling unification at high energy scale. Adopting a minimal dark matter strategy, we consider both left and right handed triplet fermionic dark matter candidates which are stable by virtue of a remnant ${\mathcal{Z}}_2\simeq (-1{)}^{B-L}$ symmetry arising after the spontaneous symmetry breaking of left-right gauge symmetry to that of the standard model. A scalar bitriplet field is incorporated whose first role is to allow radiative decay of right handed triplet dark matter into the left handed one and a photon with energy 3.55 keV. The other role this bitriplet field at TeV scale plays is to assist in achieving gauge coupling unification at a high energy scale within a nonsupersymmetric $SO(10)$ model while keeping the scale of left-right gauge symmetry around the TeV corner. Apart from solving the neutrino mass problem and giving verifiable new contributions to neutrinoless double beta decay and charged lepton flavor violation, the model with TeV scale gauge bosons can also give rise to interesting collider signatures like diboson excess, dilepton plus two jets excess reported recently in the large hadron collider data.

A systematic analysis of the structure of single-baryon correlation functions calculated with lattice QCD is performed, with a particular focus on characterizing the structure of the noise associated with quantum fluctuations. The signal-to-noise problem in these correlation functions is shown, as long suspected, to result from a sign problem. The log-magnitude and complex phase are found to be approximately described by normal and wrapped normal distributions respectively. Properties of circular statistics are used to understand the emergence of a large time noise region where standard energy measurements are unreliable. Power-law tails in the distribution of baryon correlation functions, associated with stable distributions and “Lévy flights,” are found to play a central role in their time evolution. A new method of analyzing correlation functions is considered for which the signal-to-noise ratio of energy measurements is constant, rather than exponentially degrading, with increasing source-sink separation time. This new method includes an additional systematic uncertainty that can be removed by performing an extrapolation, and the signal-to-noise problem reemerges in the statistics of this extrapolation. It is demonstrated that this new method allows accurate results for the nucleon mass to be extracted from the large-time noise region inaccessible to standard methods. The observations presented here are expected to apply to quantum Monte Carlo calculations more generally. Similar methods to those introduced here may lead to practical improvements in analysis of noisier systems.

Euclidean two-point correlators of the energy-momentum tensor (EMT) in SU(3) gauge theory on the lattice are studied on the basis of the Yang-Mills gradient flow. The entropy density and the specific heat obtained from the two-point correlators are shown to be in good agreement with those from the one-point functions of EMT. These results constitute a first step toward the first principle simulations of the transport coefficients with the gradient flow.

We study the dimensional aspect of the geometry of quantum spaces. Introducing a physically motivated notion of the scaling dimension, we study in detail the model based on a fuzzy torus. We show that for a natural choice of a deformed Laplace operator, this model demonstrates quite nontrivial behavior: the scaling dimension flows from 2 in IR to 1 in UV. Unlike another model with a similar property, the so-called Horava-Lifshitz model, our construction does not have any preferred direction. The dimension flow is rather achieved by a rearrangement of the degrees of freedom. In this respect the number of dimensions is deceptive. Some physical consequences are discussed.